LIN communication circuit and a method of communicating between LIN busses

ABSTRACT

In aspects, a Local Interconnect Network (LIN) communication circuit including a first LIN master associated with a first LIN bus and a second LIN master associated with a second LIN bus is disclosed. A data link is connected between the first and second LIN masters. A first mirroring client is established at the first LIN master for receiving message bits corresponding to a LIN message in a first slot on the first LIN bus and for transmitting the message bits bitwise over the data link. A second mirroring client is established at the second LIN master for receiving the message bits and transmitting them over the second LIN bus. The first and second LIN masters include synchronised schedule tables such that the message bits on the second LIN bus are transmitted in a corresponding slot to the first.

INCORPORATION BY REFERENCE

This application claims priority to European Patent Application NumberEP21182844.7, filed Jun. 30, 2021, the disclosure of which isincorporated by reference in its entirety.

BACKGROUND

LIN (Local Interconnect Network) bus is a low-cost serial networkprotocol used in vehicles to provide communications between components,such as windows, wipers and air conditioning controls. In most currentvehicle EE architectures, LIN communications will typically becontrolled from LIN masters within a small number of Electronic ControlUnits (ECUs). As a result, a large quantity of cabling is requiredbetween the ECUs and LIN slave nodes located around the vehicle.However, as the prevalence of electronics within vehicles increases, thecable harnesses required to establish these connections have become bothlarger and more complex.

More recently, there has been a shift toward zonal EE architectures,where a limited number of zone controllers or zonal gateways are used tosupport both power distribution and data connection requirements withina particular region of the vehicle. This has the potential to providesignificant advantages in terms of reductions in complexity and wiringcosts. However, LIN communications are difficult to implement withinzonal architectures because of the changes that arise from transferringsignals from a LIN slave in one zone to a LIN slave in another.

In this connection, under the LIN communication protocol, a LIN slave isonly able to transmit messages to other LIN slaves within the samecluster (i.e., they share a common LIN master and are on a common LINbus). As such, when different LIN masters are be provided in differentvehicle zones, direct communications between physical LIN slaves indifferent zones are not possible. This creates issues where nodes indifferent zones relate to a function that would otherwise be served by asingle LIN cluster.

Although it is possible to distribute LIN messages to different regionsof the vehicle using the CAN bus, this doesn't address the above issuebecause the resultant communication is nevertheless between two separatephysical LIN networks. As such, further additional complexities andcosts are introduced to manage the communications between the differentbusses. For example, it becomes much more complex to initiate thecontrol to wake-up a remote LIN network. These issues become even morecomplex because different nodes and ECUs may be designed andmanufactured by different departments or entities, and may be used indifferent configurations in different vehicles. Consequently, even minorconfiguration changes can become very expensive. This therefore negatesmany of the advantages of using LIN bus in the first place.

The present disclosure is therefore directed to addressing issues withconventional arrangements.

SUMMARY

According to a first aspect there is provided a LIN communicationcircuit including: a first LIN master associated with a first LIN bus; asecond LIN master associated with a second LIN bus; a data linkconnecting between the first and second LIN masters; a first mirroringclient established at the first LIN master for receiving message bitscorresponding to a LIN message in a first slot on the first LIN bus andtransmitting the message bits bitwise over the data link; and a secondmirroring client established at the second LIN master for receiving themessage bits from the data link and transmitting the message bits overthe second LIN bus, wherein the first and second LIN masters includefirst and second schedule tables respectively, and wherein the first andsecond schedule tables are synchronised such that the message bitstransmitted on the second LIN bus are transmitted in a correspondingfirst slot to the first slot on the first LIN bus.

In this way, communication between different LIN clusters may befacilitated without needing to alter the configuration of the LIN slavenodes. This thereby allows standard, low cost LIN slaves to be usedwithin a zonal EE architecture. That is, LIN slave nodes in differentzones of a vehicle may convey information to each other through a datalink, such as an ethernet, PCIe, or hardware cache coherentinterconnect. This thereby allows LIN slaves to be effectively mirroredacross one or more clusters without altering the LIN protocol.

In implementations, the circuit further includes a synchroniser forsynchronising the first and second schedule tables. In implementations,the second schedule table is adjusted to specify a jitter time for thecorresponding first slot which is longer than a jitter time for thefirst slot specified in the first schedule table. In this way, the timerequired to transmit data through the data link may, at least in part,be accommodated by adjusting the jitter specification in the secondschedule table. The synchroniser may adjust the second schedule table,for example based on a preprogramed adjustment factor.

In implementations, the second schedule table is adjusted to specify aninter-byte space for the corresponding first slot which is longer thanan inter-byte space specified for the first slot in the first scheduletable. In this way, the time required to transmit data through the datalink may, at least in part, be accommodated by adjusting the inter-bytespace specification in the second schedule table.

In implementations, the circuit further includes a synchronisation linkconnecting between the first and second LIN masters for conveyingschedule data for synchronising the first and second schedule tables. Inimplementations, the synchronisation link may be part of a ethernet,PCIe, or hardware cache coherent interconnect link between zones.

In implementations, the circuit further includes a first LIN slave nodeconnected to the first LIN bus for transmitting the LIN message in thefirst slot in response to a message header in the first slot from thefirst LIN master. In this way, a standard LIN slave node may be used totransmit a message in the message field of the first slot, in responseto receipt of an associated identifier in the header field of the firstslot from the LIN master.

In implementations, the circuit further includes a second LIN slave nodeconnected to the second LIN bus for receiving the LIN message in thecorresponding first slot. In this way, a standard LIN slave node mayreceive the mirrored LIN message on the second LIN bus.

In implementations, at least one of the first and second LIN masters areElectronic Control Units (ECUs). In implementations, the LIN masters maybe Zonal ECUs or Zonal Gateways for functioning as hubs for systemswithin a zone of a vehicle.

According to a second aspect there is provided a method of communicatingbetween LIN busses, the method including: establishing a first mirroringclient at a first LIN master associated with a first LIN bus;establishing a second mirroring client at a second LIN master associatedwith a second LIN bus; receiving, by the first mirroring client, messagebits corresponding to a LIN message in a first slot on the first LIN busand transmitting the message bits bitwise over a data link connectingbetween the first and second LIN masters; and receiving, by the secondmirror client, the message bits from the data link and transmitting themessage bits over the second LIN bus, wherein the first and second LINmasters include first and second schedule tables respectively, andwherein the first and second schedule tables are synchronised such thatthe message bits transmitted on the second LIN bus are transmitted in acorresponding first slot to the first slot on the first LIN bus.

In implementations, a jitter time specified in the second schedule tablefor the corresponding first slot is longer than a jitter time specifiedin the first schedule table for the first slot.

In implementations, the jitter time specified in the second scheduletable for the corresponding first slot is a maximum defined jitter.

In implementations, an inter-byte space specified in the second scheduletable for the corresponding first slot is longer than an inter-bytespace specified in the first schedule table for the first slot.

In implementations, the method further includes the steps of:transmitting a message header in the first slot from the first LINmaster, wherein the message header identifies a first LIN slave node;and transmitting the LIN message in the first slot from the first LINslave node in response to the message header. In this way, a standardLIN protocol may be adhered to, with an identifier being transmittedfrom the LIN master in the header field of the first slot, and the LINslave node transmitting its message in the message field of the sameslot.

In implementations, the method further includes the steps of:transmitting a corresponding message header in the corresponding firstslot from the second LIN master, wherein the corresponding messageheader identifies the first LIN slave node, and wherein the step oftransmitting the message bits over the second LIN bus includestransmitting the LIN message from the second mirror client in thecorresponding first slot. In this way, a standard LIN protocol may bereplicated in the second LIN bus, with an identifier being transmittedfrom the LIN master in the header field of the corresponding first slot,and the second mirror client emulating the first LIN slave node bytransmitting its message in the message field of the same slot.

In implementations, the step of transmitting the message bits bitwiseover the data link includes bitwise slicing the LIN message by the firstmirroring client, and multiplexing the sliced bits with other data. Inthis way, rather than delaying transmission until a complete protocoldata unit has been received, the LIN message is sliced bitwise to allowconstituent bits to be transmitted. In implementations, the bits aretransmitted as a synchronous data signal.

In implementations, the method further includes the step of generating,by a virtual LIN slave node on the first LIN master, the message bitscorresponding to the LIN message in a first slot on the first LIN bus.In this way, a LIN master may establish a virtual LIN slave node withinits ECU environment and transmit messages from this virtual node to oneor more other LIN busses.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative implementations will now be described with reference to theaccompanying drawings in which:

FIG. 1 shows a schematic communication circuit according to a firstimplementation; and

FIG. 2 shows a schematic communication circuit according to a secondimplementation.

DETAILED DESCRIPTION

FIG. 1 shows a first illustrative implementation of a communicationcircuit 100. The communication circuit 100 includes a first LIN cluster10 and a second LIN cluster 20. Each of the clusters 10,20 arecontrolled by a respective first and second LIN master 1,2, with eachmaster being provided as an electronic control unit in a different zoneof the vehicle. As such, they are programmable zonal control unitscapable of implementing functions in addition to their master taskfunctions on the LIN bus. They are also physically separated from eachother.

Each LIN master 1,2 includes a schedule table 14,24 for managing thetiming of frame slots and traffic control on their respective LIN bus.Each LIN master 1,2 is further provided with an interface 15,25 forconnecting to a respective LIN line 12,22 which physically implementsthe LIN bus and is associated with a plurality of LIN slaves 11 a-c,21a-c. As such, the first and second groups of LIN slaves 11 a-c,21 a-cform the LIN cluster 10,20 with their respective first and second LINmasters 1,2. Communications on the first LIN line 12 from the firstgroup of LIN slaves 11 a-c are controlled by the first LIN master 1, andcommunications on the second LIN line 22 from the second group of LINslaves 21 a-c are controlled by the second LIN master 2.

A data link 16 and a synchronisation link 17 are further providedbetween the interfaces 15,25 of the first and second LIN masters 1,2. Inthis implementation, these links are provided through an Ethernettime-sensitive networking (TSN) connection. This thereby provides highspeed communication between the LIN masters 1,2. In otherimplementations, other types of data link may be used, such as aPeripheral Component Interconnect Express (PCIe) or a Cache CoherentInterconnect. It will be appreciated that although the schematicillustration shows the data link 16 and synchronisation link 17 as twoseparate links, in practice the signals may be provided over a sharedconnection. For instance, they may be provided as different channels ona common communication line.

As mentioned above, the LIN masters 1,2 are electronic control units andare capable of establishing virtual LIN slaves internally for performingslave node functions in addition to their master task functions. Assuch, virtual LIN slaves may be implemented in software within the LINmasters 1,2, and the schedule tables 14,24 in each master may allocateslots for communications by the virtual LIN slaves on the LIN bus as ifthey were physical slaves connected to the respective LIN line. It willbe appreciated that, by virtue of their implementation in software, thevirtual LIN slaves may also perform additional functions, as isdescribed in further detail below.

As shown in FIG. 1 , the LIN masters 1,2 each implement a virtual LINslave to function as first and second mirroring clients 13,23. The firstand second mirroring clients 13,23 are communicatively connected overthe data link 16.

The first mirroring client 13 in the first LIN master 1 is configured toread messages from the first LIN line 12 in a bitwise manner andtransmit those data bits over the data link 16. That is, rather thanreading and transmitting a complete LIN Protocol Data Unit (PDU), thefirst mirroring client 13 reads individual bits such that these bits aretransferred over the data link 16. In implementations where a number ofLIN clusters are provided in a single zone, the individual bits frommultiple LIN clusters may be multiplexed together for transmission overthe data link 16 along with other data generated by the zonal ECU. Inthis implementation, the other data includes data for safety andsecurity mechanisms which is verified by the second LIN master 2 onreceipt.

At the same time as the above, the second mirroring client 23 in thesecond LIN master 2 reads the bitwise data transmitted over the datalink 16 and relays this over the second LIN line 22. As such, the secondmirroring client 23 functions as a proxy for the respective first LINslave whose message is conveyed over the data link 16.

In this connection, imagine a scenario where a first LIN slave 11 a inthe first LIN cluster 10 needs to transmit a message to a second LINslave 21 a in the second LIN cluster 20. The first LIN master 1 willinitiate a message header including an identifier to prompt the firstLIN slave 11 a to transmit its message in the message field of the sameslot on the first LIN line 12. This is received by the first mirroringclient 13 and is transmitted over the data link 16. The second mirroringclient 23 in the second LIN cluster 20 in turn transmits this over thesecond LIN line 22. As such, the second mirroring client 23 replicatesthe effect of the first LIN slave 11 a existing on the second LIN line22.

To facilitate the above, the first and second schedule tables 14,24 aresynchronised such that the slot for the transmission of the first LINslave 11 a's message exists in both the first and second clusters 10,20.The synchronisation is achieved through the synchronisation link 17,under the control of the synchroniser 19, which is implemented in thesoftware of the first and second masters 1,2. Whilst synchronising theslots, the synchroniser 19 modifies the second schedule table 24 so thatthe jitter and inter-byte space for the slot containing the first LINslave message field is adjusted to be closer to the maximum definedjitter and inter-byte space under the LIN specification. That is, if thedetermined time taken for the second mirroring client 23 to read andtransmit a bit on the second LIN line 22 is, for instance, 56 μs, thesecond schedule table 24 may set the jitter to 100 μs. This therebyprovides a 44 μs window in which a data bit may be transmitted over thedata link 16 from the first LIN cluster 10 to the second LIN cluster 20whilst still appearing in effectively the same slot. Accordingly, whenthe message is transmitted by the first LIN slave 11 a, it will be atthe start of the message field within the slot. On the receiving end,the data bits will be transmitted on the second LIN line 22 in a messagefield which is later in a slot corresponding to the first, as providedby the second schedule table 24. Accordingly, although there is atransmission delay as the data bits are relayed through the data link16, this is absorbed by the redundancy built into the LIN protocol andprovided by the jitter and inter-byte spaces. Consequently, from theperspective of the second slave device 21 a, the received message willappear to have been transmitted from a slave node in the same cluster20. Accordingly, even though the first slave device 11 a is distributedin a different zone, it may be configured in the same way as if it werepart of the second LIN cluster 20. This thereby allows standard LINslave nodes to be easily utilised within a zonal architecture.

It will be understood that the second schedule table needs only toadjust timing within slots associated with LIN communications from otherclusters. For communications within the same cluster, normal jitter andinter-byte spacing may be used.

The synchronisation link 17 allows the schedule tables 14,24 to beupdated as needed to facilitate communications between other LIN slaves,both from the first cluster 10 to the second 20 and in the reverse.

To ensure that the LIN schedule tables 14,24 are synchronised, one ofthe tables is preselected as a master table, and the other scheduletable is updated based on the master table. In other implementations, aconsensus algorithm may be used to select the master table based on, forexample, the LIN master with the shortest connections to connected LINmasters.

Error handling may be implemented using sporadic frames to promptsynchronous error checking.

The above arrangement also allows for the provision of virtual LIN slavenodes on one LIN master to communicate to a plurality of LIN clustersassociated with different LIN Masters. In this respect, FIG. 2 shows asecond implementation which is substantially identical to the firstimplementation except that a virtual LIN slave 18 is further provided inthe first LIN master 1. As with the previous implementation, both thefirst and second LIN masters 1,2, implement mirroring clients 13,23. Asbefore, the virtual LIN slave 18 is triggered by the schedule table 14in the first LIN master, which prompts the virtual LIN slave 18 totransmit its message. This is then transferred via the mirroring clients13,23 and the data link 16 to the second LIN cluster 20. In practice, itwill be understood that the virtual LIN slave 18 may be located inanother ECU device connected via the data link 16, with the schedulingtables being synchronised such that the virtual LIN slave 18 istriggered before the start of the corresponding slots allocated to themirroring clients in the connected LIN clusters. As such, the respectiveconnected LIN masters 2 will transmit the header and slave ID for thevirtual LIN slave 18, with the transmission timing resulting in themirroring clients 13,23 generating the message received by the virtualLIN slave 18 on their respective LIN line in the appropriate messagefield.

Accordingly, the above arrangements, communication between LIN clientsin different zones of the vehicle may be facilitated without needing toalter the configuration of the LIN slave nodes. This thereby allowsstandard, low cost LIN slaves to be used within a zonal EE architecture.

It will be understood that the implementation illustrated above showapplications only for the purposes of illustration. In practice,implementations may be applied to many different configurations, thedetail of which being straightforward for those skilled in the art toimplement.

What is claimed is:
 1. A Local Interconnect Network (LIN) communicationcircuit comprising: a first LIN master associated with a first LIN bus;a second LIN master associated with a second LIN bus; a data linkconnecting between the first and second LIN masters; a first mirroringclient established at the first LIN master for receiving message bitscorresponding to a LIN message in a first slot on the first LIN bus andtransmitting the message bits bitwise over the data link; and a secondmirroring client established at the second LIN master for receiving themessage bits from the data link and transmitting the message bits overthe second LIN bus, wherein the first and second LIN masters comprisefirst and second schedule tables respectively, and wherein the first andsecond schedule tables are synchronised such that the message bitstransmitted on the second LIN bus are transmitted in a first slot on thesecond LIN bus corresponding to the first slot on the first LIN bus, thesecond schedule table adjusted such that at least one of a jitter or aninter-byte space is adjusted based on a LIN specification.
 2. A LINcommunication circuit according to claim 1, further comprising asynchroniser for synchronising the first and second schedule tables, thesecond schedule table is adjusted to specify a jitter time for the firstslot on the second LIN bus which is longer than a jitter time for thefirst slot specified in the first schedule table.
 3. A LIN communicationcircuit according to claim 1, wherein the second schedule table isadjusted to specify an inter-byte space for the first slot on the secondLIN bus which is longer than an inter-byte space specified for the firstslot in the first schedule table.
 4. A LIN communication circuitaccording to claim 1, further comprising a synchronisation linkconnecting between the first and second LIN masters for conveyingschedule data for synchronising the first and second schedule tables. 5.A LIN communication circuit according to claim 1, further comprising afirst LIN slave node connected to the first LIN bus for transmitting theLIN message in the first slot in response to a message header in thefirst slot from the first LIN master.
 6. A LIN communication circuitaccording to claim 1, further comprising a second LIN slave nodeconnected to the second LIN bus for receiving the LIN message in thefirst slot on the second LIN bus.
 7. A LIN communication circuitaccording to claim 1, wherein at least one of the first and second LINmasters are Electronic Control Units.
 8. A method of communicatingbetween LIN busses, the method comprising: establishing a firstmirroring client at a first LIN master associated with a first LIN bus;establishing a second mirroring client at a second LIN master associatedwith a second LIN bus; receiving, by the first mirroring client, messagebits corresponding to a LIN message in a first slot on the first LIN busand transmitting the message bits bitwise over a data link connectingbetween the first and second LIN masters; and receiving, by the secondmirror client, the message bits from the data link and transmitting themessage bits over the second LIN bus, wherein the first and second LINmasters comprise first and second schedule tables respectively, andwherein the first and second schedule tables are synchronised such thatthe message bits transmitted on the second LIN bus are transmitted in afirst slot on the second LIN bus corresponding to the first slot on thefirst LIN bus, the second schedule table adjusted such that at least oneof a jitter or an inter-byte space is adjusted based on a LINspecification.
 9. The method according to claim 8, wherein a jitter timespecified in the second schedule table for the first slot on the secondLIN bus is longer than a jitter time specified in the first scheduletable for the first slot.
 10. The method according to claim 9, whereinthe jitter time specified in the second schedule table for the firstslot on the second LIN bus is a maximum defined jitter.
 11. The methodaccording to claim 8, wherein an inter-byte space specified in thesecond schedule table for the first slot on the second LIN bus is longerthan an inter-byte space specified in the first schedule table for thefirst slot.
 12. The method according to claim 8, further comprising:transmitting a message header in the first slot from the first LINmaster, the message header identifying a first LIN slave node; andtransmitting the LIN message in the first slot from the first LIN slavenode in response to the message header.
 13. The method according toclaim 8, further comprising: transmitting a corresponding message headerin the first slot on the second LIN bus from the second LIN master, thecorresponding message header identifying a first LIN slave node,transmitting the message bits over the second LIN bus comprisestransmitting the LIN message from the second mirror client in the firstslot on the second LIN bus.
 14. The method according to claim 8, whereinthe step of transmitting the message bits bitwise over the data linkcomprises bitwise slicing the LIN message by the first mirroring client,and multiplexing the sliced bits with other data.
 15. The methodaccording to claim 8, further comprising: generating, by a virtual LINslave node on the first LIN master, the message bits corresponding tothe LIN message in a first slot on the first LIN bus.
 16. A LocalInterconnect Network (LIN) communication circuit comprising: a first LINmaster associated with a first LIN bus; a second LIN master associatedwith a second LIN bus; a data link connecting between the first andsecond LIN masters; a first mirroring client established at the firstLIN master for receiving message bits corresponding to a LIN message ina first slot on the first LIN bus and transmitting the message bitsbitwise over the data link; a second mirroring client established at thesecond LIN master for receiving the message bits from the data link andtransmitting the message bits over the second LIN bus, wherein the firstand second LIN masters comprise first and second schedule tablesrespectively; and a synchroniser for synchronising the first and secondschedule tables such that the message bits transmitted on the second LINbus are transmitted in a first slot on the second LIN bus correspondingto the first slot on the first LIN bus, the second schedule tableadjusted to specify a jitter time for the first slot which is longerthan a jitter time for the first slot specified in the first scheduletable.
 17. A LIN communication circuit according to claim 16, furthercomprising a synchronisation link connecting between the first andsecond LIN masters for conveying schedule data for synchronising thefirst and second schedule tables.
 18. A LIN communication circuitaccording to claim 16, further comprising a first LIN slave nodeconnected to the first LIN bus for transmitting the LIN message in thefirst slot in response to a message header in the first slot from thefirst LIN master.
 19. A LIN communication circuit according to claim 16,further comprising a second LIN slave node connected to the second LINbus for receiving the LIN message in the first slot on the second LINbus.
 20. A LIN communication circuit according to claim 16, wherein atleast one of the first and second LIN masters are Electronic ControlUnits.